Banning a service because it "might be used for illegal purposes" is insufficient. This is a problem with law enforcement in general: they are lazy and seek to have automated solutions to so much of what used to be called police work. This applies to warrant-less wiretaps, pulling information on people from 3rd party data brokers to side-step warrant and FOIA requirements, and more. I would rather money-launderers ge…
So this isn't Tornado Cash "might be used for illegal purposes" so much as it's clear evidence they're failing to meet their legal obligations.
There's a larger point here too: as much as proponents tour crypto's extragovernmental status, it would take very little effort by governments to completely cripple any crypto assset in practical terms.